1. Field of the Invention
The present invention generally relates to a charge pump circuit. More specifically, the present invention relates to a charge pump circuit that improves power efficiency.
Priority is claimed on Japanese Patent Application No. 2008-291068, filed Nov. 13, 2008, the content of which is incorporated herein by reference.
2. Description of the Related Art
In recent years, LSI (large-scale integrated) circuits, such as semiconductor memory devices, have required multiple internal power voltages such as 3V, 5V, and 10V. In addition, in many cases, the LSI circuit requires a high voltage. Therefore, a charge pump circuit is used in order to boost a single external power voltage to generate a plurality of voltages.
The charge pump circuits are mainly classified into a parallel type, a serial type, and a serial-parallel type. For example, Japanese Unexamined Patent Application, First Publication, No. JP-A-2008-161014 discloses a serial-type charge pump circuit.